The invention relates to a pocket chain wheel having two groups of pockets for chain links passing the wheel at a tilt, said groups of pockets being arranged side by side in a view perpendicular to the wheel axis, in which the pockets of the one group are offset relative to the pockets of the other group, in the peripheral direction of the wheel, by half a pocket pitch respectively, and in which the pockets exhibit bases, for supporting the legs facing the wheel axis, and bearing surfaces, formed by webs, for supporting those legs of the chain links which are facing away from the wheel axis.
A pocket chain wheel of the above type is known from U.S. Pat. No. 4,108,014. In this pocket chain wheel, the pockets support those legs of the chain links which face the wheel axis across virtually the whole of their length, i.e. from the middle of the link into the region of the link nose ends, whilst the support of the legs facing away from the wheel axis is attended to by flat bearing surfaces formed by webs which form partitions between successive pockets, a chain member being supported, in each case, on the base of the one pocket group and the webs of the other pocket group. The use of the known chain wheel in chain hoists leads to problems wherever there are relatively large loads to be lifted rapidly. The stresses which arise in such cases result in premature chain link fractures, the cause of which can be sought, in particular, in adverse bending stresses upon the chain link legs. It has herein been assumed that these bending stresses are triggered by the weld bulges of the chain links and, for this reason, the centers of the flat bearing surfaces have been furnished with recesses for the weld bulges. A notable improvement in the described circumstances has not however been achieved.